Retarders

ABSTRACT

A railroad car retarder, adapted for installation in a classification yard or the like, and of the weight-compensating type, is so constructed as to reduce substantially the hydraulic requirements used for positioning the retarder. This is accomplished by operating four rock shafts simultaneously from a single source of power.

United States Patent 1191 Wilson et al.

14 1 Oct. 9, 1973 [5 RETARDERS 75] inventors: Rosser L. Wilson, Mahwah, N.J.;

Earl E. Frank, Tallman, N.Y.

[73] Assignee: Abex Corporation, New York, NY.

[22] Filed: Apr. 22, 1971 [21] Appl. No.: 136,419

52 us. c1. 188/62 511 mm ..B6lk 7/02 [58] Field of Search 188/62 [56] References Cited UNITED STATES PATENTS 952,494 3/1910 Atwood 188/62 1,576,623

3/ 1926 Barr 1,627,137 5/1927 Barr 188/62 2,068,731 1/1937 Brown... 188/62 2,815,097 12/1957 Marsh 188/62 3,227,246 1/1966 Wilson 188/62 Primary Examiner-Duane A. Reger Att0rney--Kinzer and Dorn [5 7 ABSTRACT A railroad car retarder, adapted for installation in a classification ,yard or the like, and of the weightcompensating type, is so constructed as to reduce substantially the hydraulic requirements used for positioning the retarder. This is accomplished by operating four rock shafts simultaneously from a single source of power.

10 Claims, 11 Drawing Figures PAIENTEUHBI 9197s 3,763,967

SHEET lUF 4 190 g I96 20H Inventors Passer L. Wilson Earl E Frank [97' "95 I99 200 3 Dm Md ZAZ/(Mf J l'fiornega PAIENTED 91% 3,763 967 SHEET 2 HF d I Jfl I HHHH I, IE 2 'HHmu 'f ET P Hil l Inventors osser L.1A)ilsorz qr? E. Frank i} D6444. Hbornes PATENTEDBBT 98975 3763867 SHEET 39F 4 Inventors RQSSQY'LWHSOFL Earl E. Frank RETARDERS This invention relates to railroad car retarders and in particular to a retarder of the type disclosed in US. Pat. No. 3,227,246 where the lever arms of the retarder include portions which, during retardation of the car, cradle and support the traffic rail on which the car wheel moves. The lever arms present retarder elements on opposite sides of the traffic rail adapted to clasp and brake a car wheel on the traffic rail. Thus, the car wheel and the traffic rail in effect float on the lever arms so the retarder operates in response to the weight of the car, which is to say that the braking action on the car wheel by the retarder elements is proportional to the weight of the car. When braking action is desired, the retarder elements are spaced apart a lateral distance less than the width of a car wheel, and the retarder is actuated by the lateral thrust of a car wheel entering between the retarder elements. When no brake action is desired, the retarder elements are spaced apart a lateral distance greater than the width of a car wheel. The retarder elements may be spaced apart selectively for braking or no braking as desired by a cylinder which pivots the levers, as described in US. Pat. No. 3,227,246.

The primary object of the present invention is to enable the retarder to be more efficiently operated selectively and to enablethis to be done either by cylinder apparatus (fluid operated) or by a system of mechancial linkages, each of which is effective to exert a thrust on a horizontal link which operates a pair of crank arms, each of the latter being connected to a rock shaft.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention.

In the drawings:

FIG. 1 is a plan view of a retarder constructed in accordance with the present invention;

FIG. 2 is a fragmentary perspective view showing one embodiment of the invention, the retarder being in the open position;

FIG. 3 is a fragmentary perspective view of another embodiment of the invention, the retarder being in the closed or cocked position;

FIG. 3A is a detail view of yet another embodiment of the invention;

FIG. 4 is a plan view similar to FIG. 1 but on a larger vscale, and showing the retarder in its open position;

FIG. 5 is an end elevation substantially on the line 5-5 of FIG. 4;

FIGS. 6 and 7 are detail views of a crank arm;

FIG. 8 is a sectional view on an enlarged scale substantially on the line 8-8 of FIG. 4, but showing the retarder in its closed position, ready to receive a wheel; and

FIGS. 8A and 8B are detail views showing attachments which improve performance of the retarder.

Referring now to the drawings, and more particularly to FIG. 1, longitudinally spaced railway ties 10 support laterally spaced running or traffic rails 11 which serve to support the wheels of a railway car in the conventional manner.

While the retarder 13 is illustrated in FIG. 1 as being installed along only one traffic rail 11, it is to be under stood that the other traffic rail 1 1 may be provided with a like retarder identical in construction to the one disclosed in detail herein. Furthermore, the retarder 13 as illustrated in FIG. 4 is only two bays in length with a mechanical connecting link located between the two bays as will be described; there will ordinarily be a duplicate arrangement 13' of the same length as shown in FIG. 1, arranged in tandem.

The retarder 13 functions to apply brake forces to the wheels of a railway car moving therethroughJn the present instance, this is accomplished by positioning a pair of braking rails or retarder elements 15, FIG. 8, in engagement with opposed sides of a car wheel riding on the top portion 18 of the traffic rail 11, FIG. 8, thereby functioning to retard rotation of the car wheel as described in U.S. Pat. No. 3,227,246. The retarder elements-15 are shown in the form of rails for reasons of economy, but the present disclosure is not to be con strued as limited thereto.

When in a cocked or closed position, FIG. 8, the elements 15 are spaced apart a distance less than the width of the car wheel, so that their wheel-engaging surfaces 22, when engaged with the sides of the wheel, are forced outwardly by the car wheel moving between the braking rails 15. Each of the braking rails 15 is a unitary rail, and each is supported at spaced positions by a plurality of levers 25 pivotally mounted on an eccentric portion 116 of a rock shaft 102, FIG. 4, which spans a pair of adjacent railway ties 10. In this regard, each rock shaft 102, its eccentric 116, and the related supports are similar to the arrangement disclosed in FIG. 13 to 16 of U.S. Pat. No. 3,227,246 incorporated by reference herein.

Each of the braking rails 15, FIG. 8, has a web 30 overlying a horizontal plate 31 on the levers 25. The plate 31 is integrally fixed to the lever 25 and extends horizontally outward along the web 30. Each of the webs 30 is secured to a plurality of plates 31 on the respective levers 25 by bolts 32 inserted through elongated holes or slots (not shown) in the webs 30 and the plates 31.

The braking rails 15 are subjected to large laterally directed forces as the railroad car wheel moves between the braking rails 15 as shown and described in the aforesaid patent. The lateral forces or thrusts are transmitted by wedges 35, FIG. 8, to the levers 25. The wedges 35 serve as a solid interconnection between the rails 15 and levers 25 and afford a means of adjustment for compensation of wear, whereby the rails 15 can be moved laterally towardsthe railway wheel as described in said patent.

The levers 25 provide a monolithic structural memher which not only supports the abrasion rails 15, but which also affords cradle portion 45, FIG. 8, for sup porting the traffic rail 11. In this sense, the traffic rail floats on the cradle 45, and the weight of a car tends to depress the traffic rail.

Additionally, the levers 25 serve as the means whereby a retarding force may be exerted on the car wheel in proportion to the weight of the car being supported by the car wheels. In this connection, it will be observed that the lower or inner ends of the levers 25 are configured to embrace and support the traffic rail 11. More specifically, the movement of a car wheel through the retarding system 13 establishes lateral thrust, causing the lever arms 25 to pivot about the eccentric portions 116 of the related rock shaft 102 to lift the traffic rail 11 by virtue of the construction at the inner ends of the levers 25 as more specifically described hereinafter. The heavier the weight of the car, the greater will be the force resisting the lifting of the traffic rail 11 and the car wheel, and hence the greater the force attempting to turnthe levers 25 in an opposite direction about the related rock shaft 102 to bring the abrasion rails into tighter and greater frictional engagement with the sides of the car wheel. Thus, for heavy cars, the amount of frictional force retarding the car will be greater than that for a lighter railway car, holding the braking rails 15 in tighter engagement with the sides of the car wheel.

The cradle portion 45 of each lever 25, FIG. 8, has a central hump or rounded projection presenting a surface 46 in engagement with the under surface of the flange or base 48 of the rail 11. In addition to the supporting surface 46, the cradle 45 for the rail 11 includes an over-hanging lip or flange at the inner end of each lever 25 forming a pocket 50 for a wobble block 50A, FIG. 8, bifurcated at the inner side to loosely embrace the base 48 of the traffic rail 11. The wobble block is thus supported by the rail base for universal movement, maintaining solid engagement with the lever arm 25 and the traffic rail 11 during the time a car wheel traverses the retarder. The lever 25 is pocketed to receive loosely the wobble block 50A opposite rail 11. As an alternate the wobble block may be of the form 50A shown in FIG. 8A to afford an alternate method of attaching the wobble block to the lever 25.

Since the opposed levers 25 both have overhanging flanges 49 and wobble blocks 50A on opposite sides of the traffic rail 11, the pockets 50B serve in the aggregate to hold the traffic rail 11 against both lateral movements and rotational movements on the surface 46 of their respective cradles 45. The flanges 49 also are important from the standpoint that when the retarder system 13 is actuated to an ineffective position,

the flanges 49 assure that the levers 25 are supported by the traffic rail 11 which rests on the surfaces of the railway ties 10 when the car wheels pass thereover.

Thus it will be seen that when a lever 25 is pivoted outwardly by a car wheel entering the retarder, the inner end of each lever 25 tends to be moved upwardly, lifting the traffic rail 11 off railroad tie 10. The levers 25 thus act as large bell cranks. The upper arm of this bell crank presents the retarder element 15, the lower arm of this bell crank supports the traffic rail 11, and the pivotal axis of the bell crank is the rock shaft eccentric 116.

Each of the rock shafts 102, four in number as viewed in FIG. 4, is supported by a pair of spaced ties 10, and each has a lower rounded lobe or support portion 122 having its outer peripheral surface in position to be disposed in rolling contact with a metallic wear plate 123, FIGS. 4 and 5, disposed on the upper side of each of the supporting railroad ties 10. The rock shafts 102 are prevented from moving laterally of the ties 10 by dependent arcuate members 124, FIG. 5, thereon arranged to fit between and in close proximity to the opposed vertical faces of a pair of adjacent ties 10.

For the purposes of receiving a rotational force to rotate each rock shaft 102, the eccentric portion 116 thereof extending beyond the tie 10 is provided with a downwardly extending crank arm 135, FIG. 8, the crank arm being pinned or otherwise fixed thereto. Each crank arm 135 has an aperture 136 formed in the lower end to receive the adjacent end 104A of a link 140, FIG. 5. It will be noted that the link is reduced in diameter at each end to form the portions 140A, FIG. 4, which fit the apertures 136 of adjacent crank arms 135. The apertures 136, FIG. 6, are curved convexly to permit free play of the link ends 140A therein.

By referring to FIGS. 1 and 4 it will be observed that for each retarder bay there are, on each side of the traffic rail 11, a plurality of rock shafts 102 co-axially aligned but spaced longitudinally from one another and separated by the interposed operating link 140. The opposed ends of the rock shafts 102 are respectively provided with eccentric portions 116 on which the levers 25 are journalled, and each eccentric portion of a rock shaft has a crank arm 135 fixed thereto. Further, the lower end of each crank arm 135 receives one end of the associated operating link 140.

The operating links 140, two in number as viewed in FIG. 1, are parallel to the traffic rail 11, one on each side thereof, and are to be operated in unison. In the form of the invention shown in FIG. 4 the unitary operating means is in the form of a double-ended cylinder which extends laterally of the traffic rail 11 and which has a pair of piston rods 161 projecting therefrom. The piston rods have the usual piston heads disposed within the cylinder 160 for reciprocation by fluid under pressure, both in an outward and in an inward direction, and the free end of each piston rod 161 is provided with a clevis 162 joined to the mid-point of the respective operating link 140 by an articulating pin 165. By using a clevis and an articulating pin, and by rounding in a convex fashion, FIG. 6, the aperture 136 in the crank arm 135 it is assured that there will be ample free play in the course of actuating or setting the retarder by means of the cylinder 160.

When the retarder system 13 is in an operative position for slowing down or stopping a car, the hydraulic cylinders 160 will have been actuated to their expanded position shown in FIG. 8. The respective crank arms 135 prevent any inward movement of the rock shafts 102 along the ties 10 under the lateral forces being exerted thereon as the car wheel passes through the abrasion rails 15. Thus, the hydraulic cylinders 160 not only function to expand or contract the levers 25, as the case may be, but also serve as a means to interconnect the opposed pair of levers 25 and rock shafts 102 to prevent their inward movement relative to one another when a wheel enters the retarder.

In the event it is desired to open the retarder to the released or open state shown in FIG. 2, fluid under pressure is so supplied to the cylinder as to contract the piston rods 161 inward as viewed in FIG. 8, pulling the crank arms 135 inward. The left hand rock shaft pivots counter-clockwise, and the right hand rock shafts pivots clockwise, spreading the levers 25 and their related wheel-engaging elements 15 and allowing the car, if one is present in the retarder, to free' wheel out.

On the other hand, rotation of the crank arms 135 in response to actuating the hydraulic cylinder 160 to its expanded position, FIG. 8, causes the eccentrics 116 to turn the associated rock shafts opposite to that just described, moving the levers 25 and the opposed braking rails 15 toward one another to closed position, FIG. 8.

The amount of movement of the levers 25 and thereby the movement of the braking rails toward or away from each other is limited to a predetermined amount of movement by individual stop elements 116T, FIG. 8, on each of the eccentrics 116 rotating into engagement with an aligned stop element 2ST on an associated lever arm 25.

Limiting the amount of movement of the levers 25 is advantageous in that if one of the levers 25 should resist rotation, all of the force being generated by the hydraulic cylinder is directed to rotating the resistant lever 25, since the other lever is prevented from further rotation by engagement of the stops. Thus, rather than having one braking rail 15 move too far in one direction, with little or no movement of the other braking rail 15, the one rail is limited in its movement, and all of the hydraulic force is concentrated to move the other rail to its proper position. Additionally, since the stop elements limit the amount of the rotation of levers 25, this serves to stablize and lock in position the traffic rail 11 disposed on the supporting surfaces 46 of the levers 25.

It will be seen from the foregoing that while the levers are pivotally supported for movement laterally of the traffic rail, they are at the same time constrained against lateral shifting movement in that the cylinder 160 constrains the rock shafts from any substantial or significant rotary movement.

The operating means for pivoting the cranks 135 may take the form of a lever system, FIG. 3, including a center mounted horizontal crank 170 pivotally mounted on a vertical pin 172. In FIG. 3, the lever system has been set to the retarder-closed or cocked position. The crank 170 may be turned in either direction by a rod 173 which at one end is pivotally joined to the crank 170 and at the other end is pivotally connected to one arm of a bell crank 175, in turn pivotally mounted on a pin 176. The opposite arm of the bell crank in turn is pivotally connected to the free end of a piston rod 177 associated with a double acting cylinder 178 which may be a hydraulic cylinder or one operated by air.

A connecting link 180 is pivotally connected by clevises 181 at its opposite ends, respectively, to the end of the crank 170 opposite the rod 173 and to the mid point of the associated cross link 140 which has its ends connected to the cranks 135 in the manner described above. Similarly, a link 185 is pivotally joined by clevises 186 at the opposite ends thereof, respectively, to the mid-point of the other operating link 140 and the crank 170 in the manner shown in FIG. 3. Depending upon the direction of motion of the piston rod 177 the crank arms 135 may be turned clockwise or counterclockwise, as the case may be, incidental to turning the rock shafts 102.

Many variations are possible as to the specific form of the link system, for instance, lever 172 may be replaced by a scotch-yoke with appropriate alterations in the other connections.

The retarder in its closed or cocked position, FIG. 8, inherently tends to open or uncock by virtue of the unbalanced weight. We take advantage of this feature to allow for another mode of operation, other than by the piston rod 177. Thus we may use a so-called switchstand type device to position or operate the bell crank 175, and referring to FIG. 3A in this connection there is shown a manual positioning device 190 having a throw rod 177' extending therefrom. The throw rod 177' performs a function equivalent to piston rod 177. Thus, one end of the throw rod 177' is pivotally connected to an arm 192 fixed to a shaft 193 to be turned in a manner hereinafter described. The opposite end of the throw rod 177 is connected to the arm of the bell crank to which the piston rod 177 would otherwise be connected. It is to be understood that the lever sys tem to be operated by the bell crank 175, is the same as shown in FIG. 3.

The manual positioning device 190 includes an internal ratchet wheel 197 attached to shaft 193', and a oneway dog or pawl 198 biased by a spring (not shown) is ordinarily engaged with the teeth of the ratchet to hold the retarder in its closed or cocked position.

The pawl may be released by actuation of a rod 199 connected thereto. The rod 199 is adapted to be withdrawn from the right as viewed in FIG. 3A by the force of the operators foot applied to a pedal 200, such that by depression of the pedal 200 the pawl is released and the retarder is allowed to open before tha handle 201 is relased by the handle lock 196 as hereinafter de scribed.

The handle 201 is yoked to shaft 193 enabling the retarder to be closed or cocked, such being manifest in movement of the handle 201 counter-clockwise as viewed in FIG. 3A to re-engage the pawl and ratchet. The handle 201 is then rotated clockwise 180 to the home position where the pawl 198 acts as a one-way lock to hold the retarder in the cocked position and the handle lock 196 prevents release of the weight of the retarder until the pawl 198 is disengaged removing any possiblity of the handle 201 being relased under load.

It is of course possible to use other forms of mechanical linkage in a switch stand rather than the specific form illustrated in FIG. 3A, and in fact the safety feature may be included as part of a one-way clutch embodied in the manual positioning device 190.

In accordance with the present disclosure the lever arms 25, FIG. 8A, are provided with restraining means engaging the traffic rail to resist displacement, and the end result is .that the retarder elements 15 are restrained from bowing even though cold working may occur. Thus we attach to each lever arm 25 of the retarder, at points near the extremities of the elongated retarding elements or abrasion rails 15, a restraining arm 220, FIG. 8A. The point of attachment is also on the side of the lever opposite its hooked end 49. The restraining arm extends inwardly from the point of attachment toward the web or vertical flange of the traftic rail 1 l. The inner end of each of the restraining arms is characterized by a spacer block 222 in position to bear directly against the web of the traffic rail. In the event that the retarder elements 15, undergoing cold working, tend to warp or bow inwardly toward the traftic rail 11, this only results in the spacer blocks 222 bearing tightly against the traffic rail 11 thereby limiting the warpage tendency.

As a further assurance against disengagement of the lever arm with respect to the base or horizontal flange 48 of the traffic rail 11, spring means are interposed to urge the lever arms 25 outwardly, thereby to produce a snug fit of the wobble block 50A with the outer edge of the flange 48 of the traffic rail.

Preferably, we interpose conical coil springs 224, FIG. 8B, in the space between the vertical web 225 of the traffic rail and the adjacent surface of the lever arm 25, each coil spring being suitably supported.

The abrasion rails or retarder elements 15, FIG. 8A, are further restrained against lateral movement by restrainers 230 secured at one end to the respective lever arms by bolts 231 which also secure the restrainers 220. The opposite end of each restrainer 230 is bent upwardly at 232 to bear against the base of each retarder element, thereby anchoring each retarder element against movement due to the cold working faces above mentioned.

SUMMARY it will be seen from the foregoing that under the present invention the car retarder is characterized by pairs of large levers 25 in the form of bell cranks on opposite sides of a traffic rail. These paired levers are pivotally supported on eccentric portions of rock shafts coaxially aligned as a pair on opposite sides of the traffic rail. Each lever has an upper arm presenting an elongated retarding element engageable with the wheel, and a lower arm supporting (at 46) the traffic rail 11 so that the retarder is responsive to the weight of a car on the rail 11.

Normally, the opposed retarding elements 15 of opposed levers 25 are separated one from another less than the width of a car wheel in the closed or cocked position of the retarder. The ends of the elements 15 are flared, FIG. 1, to admit a car wheel; as the wheel progresses into the narrower space the levers 25 are spread, pivot outward on the eccentrics 116 and the lower ends thereof tend to lift the rail 11 and the car as well.

The retarder may be operated selectively by the apparatus shown in H0. 2 or by the apparatus shown in FIG. 3. in either event, expanding or contracting forces are imparted to the links 140 which in turn pivot the cranks 135 to alter the position of the eccentrics 116 thereby spreading or closing the levers 25.

In order to assure good seating and flexibility, we prefer that the hooked end 49 of the lever arm, disposed above the base of the rail, be supported flexibly by a loose fitting wobble block, itself being supported on the base of the traffic rail for universal movement or articulation. Because the retarding elements or so-called abrasion rails tend to warp due to cold working by the car wheel, we interpose a restraint to prevent this, such preferably taking the form of a rigid arm attached to each lever arm at the ends of the retarder elements and extending inwardly to bear on the traffic rail. A snug, yieldable fit is assured by the springs 224.

Hence while we have illustrated and described preferred embodiments of our invention, it is to be understood that these are capable of variation and modification.

We claim:

1. In a railroad car retarder system including a plurality of oppositely pivoting levers supporting, at their inner ends, retarding elements on opposite sides of a traffic rail for applying retarding forces to opposite sides of a car wheel on the traffic rail: a pair of rock shafts for disposition at each of the opposite sides of the traffic rail parallel thereto, each rock shaft having an eccentric portion supporting a related lever and operable when rotated to move the related lever toward and away from the traffic rail, one rock shaft at one side of the traffic rail being in substantial co-axial alignment with the other rock shaft adjacent thereto at the same side, and the ends of the rock shafts being spaced one from another, a crank arm fastened to an extension of each of the adjacent rock shafts for rotating the related rock shaft, a link joining said crank arms for operating the related levers in unison, the arrangement of paired rock shafts and arms and the joining link being repeated on the other side of the traffic rail, andoperating means joining the links to operate both links simultaneously.

2. A retarder system according to claim 1 wherein the operating means includes a fluid-driven expandable cylinder means.

3. A retarder system according to claim 2 wherein the cylinder means is a single cylinder having a pair of pistons extending therefrom with each piston connected to a related link.

4. A retarder system according to claim 1 wherein the operating means is a lever system.

5. A retarder system according to claim 4 in which the lever system includes a pivotal center-mounted crank located between the links, the crank being connected to said links, and means for turning the crank to operate the links.

6. A retarder system according to claim 5 in which the means for turning the crank includes a fluid operated piston rod.

7. A retarder system according to claim 5 in which the crank is turned by the throw rod of a manually operated positioning device.

8. Retarder apparatus for applying a retarding force to the wheels of a railroad car having its wheels supported on a traffic rail, including a pair of opposed shafts to be disposed on opposite sides of the traffic rail, a plurality of independent operating levers rotatably related to and supported by said shafts, each of said independent levers having an intermediate portion thereon to be disposed in engagement with the underside of the base of said traffic rail to lift said traffic rail when said lever is rotated in a first direction, each of said levers extending inwardly beneath the traffic rail to the side of the traffic rail opposite its support, hook means at the inner end of each of said levers at said opposite side of the traffic rail and positioned to overhang the base of the traffic rail, elongated retarder elements for applying a retarder force to the wheels ofa railroad car, said retarder elements being supported individually by. said levers on opposite sides of said traffic rail and spaced apart a distance less than the width of a railroad car wheel so that a car wheel entering the space between said opposed retarder elements causes said retarder elements to exert a force tending to rotate the levers in'said first direction to lift the traffic rail, the lifting of the traffic rail being resisted by the weight of the railroad car on said traffic rail, and means for re-' straining warpage of the retarder elements due to coldworking exerted thereon by a car wheel, said restraining means being in the form of rigid arms attached to the levers at points adjacent the opposite ends of the retarder elements, the point of attachment for each restraining arm being at the side of the traffic rail opposite the hook means of each lever, and said arms having inner end portions extended inwardly toward the traffic rail to terminate immediately adjacent the vertical flange of the traffic rail.

9. Retarder apparatus according to claim 8 wherein a wobble block associated with each lever is supported on the base of the traffic rail for universal movement relative thereto, the hook means of the associated lever in turn being supported on the wobble block.

10. Retarder apparatus according to claim 9 in which spring means acting between the traffic rail and each lever arm assure a snug fit of the wobble block.

a: m w m 

1. In a railroad car retarder system including a plurality of oppositely pivoting levers supporting, at their inner ends, retarding elements on opposite sides of a traffic rail for applying retarding forces to opposite sides of a car wheel on the traffic rail: a pair of rock shafts for disposition at each of the opposite sides of the traffic rail parallel thereto, each rock shaft having an eccentric portion supporting a related lever and operable when rotated to move the related lever toward and away from the traffic rail, one rock shaft at one side of the traffic rail being in substantial co-axial alignment with the other rock shaft adjacent thereto at the same side, and the ends of the rock shafts being spaced one from another, a crank arm fastened to an extension of each of the adjacent rock shafts for rotating the related rock shaft, a link joining said crank arms for operating the related levers in unison, the arrangement of paired rock shafts and arms and the joining link being repeated on the other side of the traffic rail, and operating means joining the links to operate both links simultaneously.
 2. A retarder system according to claim 1 wherein the operating means includes a fluid-driven expandable cylinder means.
 3. A retarder system according to claim 2 wherein the cylinder means is a single cylinder having a pair of pistons extending therefrom with each piston connected to a related link.
 4. A retarder system according to claim 1 wherein the operating means is a lever system.
 5. A retarder system according to claim 4 in which the lever system includes a pivotal center-mounted crank located between the links, the crank being connected to said links, and means for turning the crank to operate the links.
 6. A retarder system according to claim 5 in which the means for turning the crank includes a fluid operated piston rod.
 7. A retarder system according to claim 5 in which the crank is turned by the throw rod of a manually operated positioning device.
 8. Retarder apparatus for applying a retarding force to the wheels of a railroad car having its wheels supported on a traffic rail, including a pair of opposed shafts to be disposed on opposite sides of the traffic rail, a plurality of independent operating levers rotatably related to and supported by said shafts, each of said independent levers having an intermediate portion thereon to be disposed in engagement with the underside of the base of said traffic rail to lift said traffic rail when said lever is rotated in a first direction, each of said levers extending inwardly beneath the traffic rail to the side of the traffic rail opposite its support, hook means at the inner end of each of said levers at said opposite side of the traffic rail and positioned to overhang the base of the traffic rail, elongated retarder elements for applying a retarder force to the wheels of a railroad car, said retarder elements being supported individually by said levers on opposite sides of said traffic rail and spaced apart a distance less than the width of a railroad car wheel so that a car wheel entering the space between said opposed retarder elements causes said retarder elements to exert a force tending to rotate the levers in said first direction to lift the traffic rail, the lifting of the traffic rail being resisted by the weight of the railroad car on said traffic rail, and means for restraining warpage of the retarder elements due to cold working exerTed thereon by a car wheel, said restraining means being in the form of rigid arms attached to the levers at points adjacent the opposite ends of the retarder elements, the point of attachment for each restraining arm being at the side of the traffic rail opposite the hook means of each lever, and said arms having inner end portions extended inwardly toward the traffic rail to terminate immediately adjacent the vertical flange of the traffic rail.
 9. Retarder apparatus according to claim 8 wherein a wobble block associated with each lever is supported on the base of the traffic rail for universal movement relative thereto, the hook means of the associated lever in turn being supported on the wobble block.
 10. Retarder apparatus according to claim 9 in which spring means acting between the traffic rail and each lever arm assure a snug fit of the wobble block. 